In earlier development, a semiconductor wafer has been widely used for a semiconductor element such as a luminous element and light receiving element, in which a III-V group ternary or quaternary compound semiconductor layer such as an InGaAs layer, AlGaAs layer, InAlAs layer, InAlGaAs layer and InGaAsP layer and an InP layer are sequentially grown onto an InP substrate by epitaxial growth. The epitaxial layer of this semiconductor wafer is, for example, formed by metal organic chemical vapor deposition (hereinafter referred to as an MOCVD method).
However, when epitaxial growth of the above-described III-V group compound semiconductor is performed by the MOCVD method, it has been problematic that hillock-like defect occurs on the surface of the epitaxial layer to cause inferior surface morphology. Therefore, various techniques for improving surface morphology of the epitaxial layer have been developed.
For example, JP2750331B (patent document 1) discloses that plane orientation of a substrate in epitaxial growth is regulated in order to reduce a teardrop-like defect (synonymous with a hillock-like defect) occurring on a surface of a growth film. Concretely, plane orientation of a compound semiconductor single crystal substrate to be used is regulated according to a growth temperature and growth rate in growing the epitaxial layer, so that an occurrence of the teardrop-like defect is effectively reduced.
Further, a similar technique with the above patent document 1 is disclosed in Journal of Crystal Growth 129(1993) P456-464, M. Nakamura et al. (non-patent literature 1).
However, when a III-V group compound semiconductor layer such as InGaAs layer, AlGaAs layer, AlInAs layer and AlInGaAs layer is grown on a InP substrate by the above-described technique of prior art, aberrant rough morphology different from hillock-like defect is sometimes observed on a surface of an epitaxial growth layer (hereinafter referred to as aberrant surface morphology) (see FIG. 1).
The present invention is made in order to solve the above problems. The object of the invention is to provide an epitaxial growth method and a substrate for growth used for epitaxial growth, in which occurrence of the aberrant surface morphology is effectively prevented in a course of growing a III-V group compound semiconductor layer such as InGaAs layer, AlGaAs layer, AlInAs layer and AlInGaAs layer on a InP substrate.